Status of the enigmatic fossil vesicomyid bivalve Pleurophopsis

摘要

The status of the vesicomyid genus Pleurophopsis Van Winkle, 1919, which occurs in chemosynthetic environments, is evaluated based on a redescription of the type material and observations on subsequently collected material. It is concluded that the name Pleurophopsis should not be used because the presently known material of its type species, P. unioides of middle Miocene age, does not show critical hinge details like nymph, subumbonal pit, and cardinal tooth 3a of the right valve. From the presently known characters, it can be concluded that Adulomya? unioides is very similar to the type species of Adulomya and Ectenagena, and it is shown that Ectenagena is a synonym of Adulomya. However, should better preserved material of P. unioides become available and confirm its close relation to Adulomya and Ectenagena, Pleurophopsis would have priority as it is the oldest of the three names.